有一张employees表,信息如下:
另有一张dept_manager表:
从employees表和dept_manager表中选取出所有的county值(包含重复值)并按county的升序排列得到如下结果:
下面查询语句正确的是:
另有一张dept_manager表:
从employees表和dept_manager表中选取出所有的county值(包含重复值)并按county的升序排列得到如下结果:
下面查询语句正确的是:
SELECT country FROM employees UNION SELECT country FROM dept_manager ORDER BY country;
SELECT country FROM employees UNION SELECT country FROM dept_manager ORDER BY country DESC;
SELECT country FROM employees UNION ALL SELECT country FROM dept_manager ORDER BY country;
SELECT country FROM employees UNION ALL SELECT country FROM dept_manager ORDER BY country DESC;